I've been unhappy with Plextor ever since my first Plextor Purchase (the Plextor Premium CD Burner). Ironically, the Plextor Premium is the second most expensive drive I own (second to my Pioneer DVR-107 only), and the least commonly used drive. In fact, up until I got my second computer, I didn't even have it hooked up regularily. I almost didn't even hook it up when I got the second computer either, it was a toss up between the Plextor Premium and a nearly dead LiteON 24101B that was recently given to me. I ended up siding with the Plextor, but it was pretty darn close.
The only reason I might be interested in the Plextor 712a is the error checking ability, but given the Plextor Premium's error checking abilities, and software limitations, I have a feeling I will be totally disappointed with it. After the reports I've seen on the Plextor 708a, I certainly wouldn't jump to the conclusion that Plextor is any kind of quality drive.
LG is proving themselves as a quality drive maker in the DVD burner industry. LiteON is self destructing practically. And Plextor is doing whatever the heck they feel like. But the thing is, that's actually NORMAL for Plextor!

Punch Cards -> Paper Tape -> Tape Drive -> 8" Floppy Diskette -> 5 1/4" Floppy Diskette -> 3 1/2" "Flippy" Diskette -> CD-R -> DVD±R -> BD-R
The Progression of Computer Media